Abstract
Mycosis fungoides is the most common cutaneous T-cell lymphoma. Although myocardial infiltration is frequent in advanced stages, symptomatic cardiac involvement is rare. We report an unusual case of rapidly progressing acute heart failure due to cardiac affection by mycosis fungoides manifested as an intracavitary mass in the right atrium. The patient received cytoreductive surgery and adjuvant radiotherapy, presenting an excellent cardiovascular outcome during follow-up. LEARNING OBJECTIVES: •Recognize mycosis fungoides as a potential cause of cardiac mass due to its visceral progression.•Note the role of cytoreductive surgery with adjuvant radiotherapy in order to relieve heart failure symptoms and improve the prognosis of the disease in the exceptional case of mycosis fungoides presenting as an isolated cardiac mass.